1. Field of the Invention
The invention relates to a friction clutch for a motor vehicle.
2. Discussion of the Prior Art
German reference DE, 36 43 272 A1 discloses a friction clutch for a motor vehicle with a centrifugal mass device, which is equipped with a compensating centrifugal mass that serves as a mass-bearing compensating system. The compensating centrifugal mass is mounted in a freely rotatable fashion relative to the actual centrifugal mass and builds up, due to its mass inertia, a resistance moment when a torsional vibration is conveyed.
The compensating centrifugal mass is equipped with spring-mounted compensating weights, which are displaced from their rest positions in dependence on centrifugal force. The compensating centrifugal mass is therefore speed-dependent. However, this compensating centrifugal mass, because of its spring connection to the compensating weight, functions with sufficient effect only in those frequency ranges determined by the springs, and may fail in other frequency ranges.
U.S. Pat. No. 5,295,411 discloses a centrifugal mass device that, serving as a mass-bearing compensating system, accommodates a circular compensating centrifugal mass in each of a plurality of circular openings. The diameter of the compensating centrifugal mass is smaller than that of the opening. A centrifugal mass device of this type has the advantage that the displacement speed of the compensating centrifugal masses is dependent on speed changes on the centrifugal mass. Thus, torsional vibrations of a certain order (preferably, vibrations of the second order, in internal combustion engines with four cylinders) can be very effectively reduced at particular amplitudes by a certain amount. However, it is not possible to influence vibrations of a different order.
Both of the aforementioned devices belong to the technical genre of absorber. As already noted, absorbers of this type can be highly effective at certain resonance speeds or certain orders, but fail at other speeds or other orders. For this reason, it is often necessary to combine such an absorber with a torsional vibration dampers, such as that discussed in German reference DE, 36 30 398 C1. This torsional vibration damper is embodied with a centrifugal mass device, which has a drive-side centrifugal mass and an output-side centrifugal mass rotatable relative thereto. The relative movement of the output-side centrifugal mass occurs in the event of displacement in the circumferential direction of coupling elements that act between the centrifugal masses and are thus actively connected to both centrifugal masses. These coupling elements consist of springs extending in the circumferential direction.
Torsional vibration dampers of the above type are suitable for filtering a complete frequency range, i.e., for damping amplitudes of different orders. Nonetheless, especially disturbing amplitudes of a certain order cannot be effectively suppressed, as is often required.
To improve the effectiveness of such a torsional vibration damper at certain frequencies or orders, it is possible to combine the torsional vibration damper with an absorber. However, given the compensating centrifugal masses located on the absorber, as well as the guide paths or joints that would be needed, a friction clutch embodied in this fashion would be heavy, large and extremely complicated in structure.